Longtime International Olympic Committee President Juan Antonio Samaranch died of cardiac arrest Wednesday at the age of 89, the hospital in Barcelona said.
He was with his family when he died, a spokesman at the Hospital Quiron Barcelona told CNN.
Samaranch was admitted to the hospital suffering from a serious heart condition, the hospital said Tuesday.
Samaranch, a Spaniard, was made an honorary life president of the IOC after stepping down from his position in 2001. He had served in the post for 21 years, making him the longest-serving IOC president.
Current IOC President Jacques Rogge took over after Samaranch stepped down.
During his tenure, Samaranch was credited with achieving financial security for the Olympic movement by maximizing television and sponsorship deals.
He remained active in sports administration after stepping down as IOC president.
"I cannot find the words to express the distress of the Olympic family," Rogge said in a statement after his death. "I am personally deeply saddened by the death of the man who built up the Olympic Games of the modern era, a man who inspired me, and whose knowledge of sport was truly exceptional.
"Thanks to his extraordinary vision and talent, Samaranch was the architect of a strong and unified Olympic movement. I can only pay tribute to his tremendous achievements and legacy, and praise his genuine devotion to the Olympic movement and its values. We have lost a great man, a mentor and a friend who dedicated his long and fulfilled life to Olympism."
Ed Hula, editor of the Olympics Web site Around the Rings, who knew and interviewed Samaranch, said he was responsible for modernizing the IOC and bringing about fundamental changes.
"He really brought the Olympics from the 20th into the 21st century by encouraging the growth in marketing revenue, TV sponsorship, that underpins the Olympic movement today," Hula told CNN. "He took steps to end the culture of bribery and vote-buying that went on with the selection of Olympic cities.
"Some say he turned a blind eye to it for a long time until he was forced to act, but when he did act, the IOC didn't shy away from punishing and sanctioning those who were involved," Hula said. "He was old world, an old-school IOC member, but at the same time he recognized the need for the IOC to become a much more modern organization."